[Estrogen receptor alpha and colocalization of Bcl-2 in hippocampus of Alzheimer's disease]

Abstract

Objective: To investigate the possible mechanism by which estrogen regulates apoptosis through the estrogen receptor.

Methods: By means of fluorescence immunocytochemistry, the present study investigated the distribution of Bcl-2 and the colocolization of Bcl-2 and ERalpha immunoreactivity in the hippocampus of 10 Alzheimer's disease (AD) patients and 10 aged controls.

Results: Bcl-2 immunoreactivity was widely distributed in neurons, concentrating predominantly on the subfields CA3 and CA4 in the stratum pyramidale of hippocampus both in controls and in AD patients. Bcl-2 staining in the labeled neuron was observed mainly in the cytoplasm and neuritic processes, but a few nuclei were also positive. Bcl-2 labeling was also detected in the astrocytes mainly in AD, but sparsely in controls. Double-labeled fluorescence immunocytochemistry showed that most Bcl-2-immunolabeled neurons also exhibited positive staining for ERalpha.

Conclusions: Estrogen may function as a regulator of apoptosis to modulate the expression of Bcl-2 in neurons and astrocytes in hippocampus of AD through ERalpha.